1. Field of the Invention
This invention is related to apparatus associated with the working of twisted wires and more particularly to apparatus for orienting twisted wires.
2. Description of the Prior Art
Apparatus for working twisted wires are well-known in the art. Thus, for example, in the publication entitled "Twisted Pair Wiring Machine", C. N. Bowman, IBM Technical Disclosure Bulletin, Volume 13, No. 2, July 1970, pages 368-369; or in U.S. Pat. No. 3,646,307, entitled "Wiring Apparatus", filed Sept. 24, 1970, and issued Feb. 29, 1972, or in U.S. Pat. No. 3,960,309, entitled "Fine Wire Twisted Pair Routing and Connecting System", both of which patents have a common inventorship and a common assignee, to wit: Herbert K. Hazel and International Business Machines Corporation, respectively, common assignee herein; or in U.S. Pat. No. 3,989,178, entitled "Wire Maze Penetrating Apparatus", filed Dec. 11, 1975, and issued Nov. 2, 1976, David E. Houser co-inventor herein, Kenneth J. Lubert, and Richard J. Morenus, co-inventor herein, and also assigned to the common assignee herein; there are disclosed apparatus where twisted wire pairs are bonded to circuit boards and the like.
In automated systems of effecting such multiple bondings such as, for example, the ones described in the aforementioned patents, it is important that the twisted wires have a particular orientation before effecting the bonding. This is particularly the case, for example, if the wires are associated with different circuit lines. For example, in a twisted wire pair generally one wire is associated with one type of circuit line, e.g. the signal line, and the other is associated with another type of circuit line, e.g. the ground line. These prior art systems, however, lacked means for orienting the twisted wires in a reliable and simple manner and often required visual inspection and/or manual intervention to insure proper orientation.
More specifically, it should be understood that in the prior art system described in the aforementioned U.S. Pat. No. 3,960,309, which is incorporated herein by reference, that when the twisted wire pair thereof is positioned at the bonding site, a determination is made of the orientation of the signal wire and ground wire of the twisted wire pair with respect to the signal and ground reflow solder pads on the workpiece to which they are to be bonded. If the determination indicates that the orientation is correct, then the bond is effected. For sake of explanation, the correct position is sometimes referred to herein as the obverse orientation. If on the other hand the determination indicates that the orientation is incorrect, the twisted wire pair feeding tool, which feeds the twisted wire pair through an axial bore of the tool, is rotated about the axial bore one hundred eighty degrees to provide the correct orientation, hereinafter sometimes referred to as the reverse orientation, prior to effecting the bonding. In this last regard, the feeding tool in effect flips, i.e. turns, the twisted wire pair upside down to provide the correct orientation in the bonding plane. It should be understood that the feeding tool is also mounted in a rotatable turret head which allows the feeding tool and, hence, the wires to be also angularly positionable about an axis substantially normal to the bonding plane.
While this last described prior art system was in general satisfactory, it has several disadvantages. For example, the aforementioned orientation determination required a visual, i.e. operator, inspection. Alternatively, it has been suggested that a combined closed TV and electronic detection circuitry, which is based on color discrimination between the two different colored insulating coverings used on the respective signal and ground wires, be utilized to make the orientation determination, cf. the publication entitled "Color Detection System", R.H. Hojaboom et al, IBM Technical Disclosure Bulletin, Vol. 19, No. 12, 1977, pages 4552-4553. In both these cases, however, the determintion was not amenable for integration into or compatible with a fully automated wire routing and bonding system and particularly if the routing and bonding system was under computer control, Moreover, these types of determination were subject to human error and in the case of the closed TV system were expensive and complex to implement. Furthermore, in this particular prior art system, the twisted wire pair after exiting from the aforementioned axial bore was adapted to be gripped by actuatable clamping jaws of the feeding tool. However, the clamping jaws and/or their actuation was not synthesized with the feeding of the twisted wire pair and/or the twisted wire pair feed was subject to slipping. Hence, there was no consistency or reliability in the prior art system, that the clamping jaws, each time they were actuated, would grip the same corresponding half-twist section for each consecutive full-twist section. As a result, in the prior art system, the twisted wire pair was in a randomly oriented one of two possible positions between the actuated clamping jaws. This randomness and concomitant unreliability was, hence, incompatible with a fully automated system.